JP2009058745A - Electrostatic charge image developing magenta toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing magenta toner having an appropriate hue angle and high saturation and moreover, having satisfactory electrostatic charging properies and superior light resistance. <P>SOLUTION: The electrostatic charge image developing magenta toner contains, at least binding resin and a magenta coloring agent. The magenta coloring agent is formed of a rhodamine-based compound, represented by a general formula (1) or its lake salt. In the general formula (1), each of R<SP>1</SP>-R<SP>4</SP>is a 1-4C alkyl group or an alkenyl group that may have a substituent, R<SP>5</SP>is a 5-20C alkyl group or alkenyl group or -OR<SP>6</SP>(wherein R<SP>6</SP>is a 5-20C alkyl group, an alkenyl group or an aryl group). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic image developing magenta toner used for electrophotographic image formation, and more particularly to an electrostatic image developing magenta toner containing a rhodamine compound and a lake salt thereof as a magenta colorant.

  In an electrophotographic image forming apparatus, full-color printing has recently become possible in addition to monochrome printing typified by conventional documents. A color image forming apparatus that performs such full-color printing can produce on-demand printed matter for the required number of sheets without causing a plate like printing, so it is mainly used in the light printing field where there are many opportunities to order small quantities of prints. (For example, refer to Patent Document 1).

  When a full-color printed product such as a catalog or an advertisement is formed by a color image forming apparatus, the toner used is required to have excellent color reproducibility so that an image faithful to the original can be obtained. That is, in full-color image formation, a target color image is reproduced by superimposing toner images relating to yellow, magenta, and cyan, and these color toners that serve as a base for faithfully reproducing the color tone are themselves. Are required to have excellent color reproducibility.

  Conventionally, azo lake pigments, anthraquinone dyes, quinacridone pigments, rhodamine compounds and lake salts thereof have been suitably used as magenta colorants constituting magenta toners for developing electrostatic images for color printing. Rhodamine compounds and lake salts thereof have high saturation and appropriate hue angles, and can provide high color development in electrophotographic image formation and can faithfully reproduce colors from red to blue. (For example, refer to Patent Documents 2 to 4).

However, since rhodamine compounds or lake salts thereof are rich in water absorbency, such magenta toners based on rhodamine compounds or lake salts are highly dependent on the humidity of the charge, and are charged in a high temperature and high humidity environment. As a result, good chargeability such as a decrease in the amount cannot be obtained, and as a result, the color balance is lost, the image density is changed, and image defects such as fogging are caused.
In addition, some rhodamine compounds or their rake salts have low weather resistance and low fastness to light and heat, so color transfer to PVC sheets and laminate films, and printed matter fades when left unattended. There is also a problem that excellent storage properties cannot be obtained.

JP-A-5-297633 JP-A-5-11504 Japanese Patent Laid-Open No. 9-179348 JP 2003-167385 A

  The present invention has been made in consideration of the circumstances as described above, and its purpose is to have an appropriate hue angle and high saturation, and also have good chargeability and excellent light resistance. An object of the present invention is to provide a magenta toner for developing an electrostatic image.

The electrostatic image developing magenta toner of the present invention comprises at least a binder resin and a magenta colorant,
The magenta colorant comprises a rhodamine compound represented by the following general formula (1) or a lake salt thereof.

[In the general formula (1), R ^{1 to} R ⁴ are each an optionally substituted alkyl group or alkenyl group having 1 to 6 carbon atoms, and R ⁵ is a carbon number having 5 to 20 carbon atoms. An alkyl group, an alkenyl group or —OR ⁶ (wherein R ⁶ is an alkyl group, alkenyl group or aryl group having 5 to 20 carbon atoms). ]

In the magenta toner for developing an electrostatic charge image of the present invention, the rhodamine compound contained in the magenta colorant is such that R ⁵ in the general formula (1) is —OR ⁶ and R ⁶ is a cyclohexyl group. ^{1 to} R ⁴ are each preferably an alkyl group or an alkenyl group having 3 to 6 carbon atoms.

  According to the magenta toner for developing an electrostatic charge image of the present invention, the magenta colorant basically comprises a specific rhodamine compound or a lake salt thereof, so that it has an appropriate hue angle and has high chroma and color turbidity. A primary color or secondary color image without vivid colors can be formed, and a color close to that of a photographic image can be reproduced, and the specific rhodamine compound or its lake salt is specified. As a result of having a hydrophobic structure, good chargeability is exhibited, such as being able to reduce the humidity dependency of charging and suppressing fluctuations in charge amount even in a high temperature and high humidity environment. In addition, a good image can be formed all the time, and sufficient fastness to light and heat can be obtained, and excellent storability can be obtained.

  Hereinafter, the present invention will be specifically described.

  The electrostatic image developing magenta toner of the present invention (hereinafter also simply referred to as “magenta toner”) contains at least a binder resin and a magenta colorant, and the magenta colorant includes: It consists of a rhodamine compound represented by the general formula (1) or a lake salt thereof (hereinafter also referred to as “specific rhodamine compound”).

In the general formula (1), R ^{1 to} R ⁴ are each an alkyl group or alkenyl group having 1 to 6 carbon atoms which may have a substituent.

Then, in the general formula (1), R ⁵ is made of bulky groups, specifically unsubstituted alkyl group having 5 to 20 carbon atoms, an alkenyl group or an -OR ^6.
Here, R < ⁶ > is a C5-C20 alkyl group, an alkenyl group, or an aryl group. R ⁶ is preferably an unsubstituted alkyl group, alkenyl group or aryl group having 5 to 20 carbon atoms.
The specific rhodamine compound or the lake salt thereof constituting the magenta colorant relating to the magenta toner of the present invention has a bulky group in which the substituent bonded to the carboxyl group or carbonyl group is bulky due to the molecular structure of rhodamine. Therefore, high hydrophobicity can be obtained, so that the magenta toner has low hygroscopicity and exhibits good chargeability.

In the general formula (1), R ⁵ is —OR ⁶ , and R ⁶ is an alkyl group, alkenyl group or aryl group having 5 to 20 carbon atoms. It can be obtained by esterifying the carboxyl group of the rhodamine compound represented by (α) with a bulky alcohol, specifically, for example, cyclohexyl alcohol, t-butyl alcohol, benzyl alcohol, neopentyl alcohol or the like.

In the general formula (alpha), R ¹ to R ^4, respectively, showing the R ¹ to R ⁴ in the general formula (1) showing a certain rhodamine compounds of interest.

In such a magenta toner, the rhodamine compound contained in the magenta colorant is a cyclic aliphatic hydrocarbon in which R ⁵ in the general formula (1) is —OR ⁶ and R ⁶ is a carbon number of 5 to 20. And R ^{1 to} R ⁴ are each preferably an alkyl group or an alkenyl group having 3 to 6 carbon atoms, and particularly preferably, R ⁶ is a cyclohexyl group, and R ^{1 to} R ^4. Are each an alkyl group or alkenyl group having 3 to 6 carbon atoms.

  Examples of the specific rhodamine-based compound constituting the magenta colorant include compounds represented by the following formulas (1-a) to (1-d).

  The content of the magenta colorant is preferably 2 to 15% by mass, more preferably 4 to 10% by mass with respect to the entire magenta toner particles.

By using the magenta colorant as described above, the visible image formed on plain paper using the obtained magenta toner has a lightness of L ^* , a red-green hue a ^* , and a yellow-blue hue. when represented by L ^* a ^* b ^* color system to b ^*, the range of hue angle, for example, paths 320 to 360 °.
Here, the L ^* a ^* b ^* system color system is a means that is useful for numerically expressing colors. L ^{* in the} z-axis direction represents lightness, and a ^{* in the} x-axis and y-axis ^. And b ^* represent hue and saturation. The lightness refers to the relative brightness of the color, the hue refers to a hue such as red, yellow, green, blue, and purple, and the saturation refers to the degree of vividness of the color.
The hue angle is, for example, a x-axis-y-axis plane representing the relationship between hue and saturation when the brightness takes a certain value, and a half line between a coordinate point (a, b) and the origin O is x An angle formed with a straight line extending in the + direction of the x-axis in the counterclockwise direction from the + direction (red direction) of the axis. In the x axis-y axis plane, the x direction of the x axis indicated by a ^* is the green direction, the + direction of the y axis indicated by b ^* is the yellow direction, and the-direction of the y axis is blue. Direction.

<Binder resin>
The binder resin can be used without any particular limitation.
Specific examples of such binder resins include styrene resins, acrylic resins such as alkyl acrylates and alkyl methacrylates, vinyl polymers such as styrene-acrylic copolymer resins, olefin resins, polyester resins, and silicones. Resin, amide resin, epoxy resin, etc., especially styrene-based, which has high transparency, low melt viscosity and high sharp melt properties in order to improve transparency and color reproducibility of superimposed images Resins and acrylic resins are preferred. These can be used alone or in combination of two or more.

  Moreover, as a polymerizable monomer for obtaining a binder resin, for example, a styrene monomer such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, chlorostyrene; methyl acrylate, ethyl acrylate, acrylic (Meth) acrylic acid ester monomers such as butyl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl hexyl methacrylate; carboxylic acid monomers such as acrylic acid and fumaric acid Can be used. These can be used alone or in combination of two or more.

  As such a binder resin, the number average molecular weight (Mn) is 3000 to 20,000, preferably 3500 to 15,000, and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2. -6, preferably 2.5-5.5, glass transition temperature (Tg) of 10-70 ° C, preferably 25-40 ° C, softening point temperature of 70-110 ° C, preferably 80-105 ° C. It is preferable to use a resin.

<Method for producing magenta toner>
The method for producing the magenta toner of the present invention comprises agglomerating and fusing fine particles comprising a binder resin (hereinafter referred to as “binder resin fine particles”) and colorant fine particles containing a magenta colorant. Specific examples include an emulsion polymerization aggregation method.

  In the emulsion polymerization aggregation method, a dispersion of binder resin fine particles produced by the emulsion polymerization method is mixed with a dispersion of toner particle constituents such as other colorant fine particles, and the repulsive force on the surface of the fine particles and the electrolyte by adjusting pH Aggregating slowly while maintaining a balance with the agglomeration force due to the addition of a coagulant composed of a body, and performing association while controlling the average particle size and particle size distribution, and at the same time, fusing between fine particles by heating and stirring This is a method for producing toner particles by performing shape control.

  The binder resin fine particles may have a structure of two or more layers made of binder resins having different compositions. In this case, the first resin prepared by emulsion polymerization treatment (first-stage polymerization) according to a conventional method. It is possible to employ a method in which a polymerization initiator and a polymerizable monomer are added to a fine particle dispersion, and this system is polymerized (second stage polymerization).

A specific example of the production process when the magenta toner of the present invention is obtained by an emulsion polymerization aggregation method is shown below.
(1) A colorant fine particle dispersion preparation step for obtaining a dispersion of colorant fine particles in which colorant fine particles containing a magenta colorant are dispersed in an aqueous medium.
(2) A polymerizable monomer solution is prepared by dissolving or dispersing toner particle constituent materials such as a release agent and a charge control agent as necessary in the polymerizable monomer to form the binder resin. Is added to an aqueous medium, mechanical energy is applied to form oil droplets, and then a polymerization reaction is carried out in the oil droplets by radicals from a water-soluble radical polymerization initiator to obtain binder resin fine particles. Resin fine particle polymerization process,
(3) Magenta toner particles that add a flocculant to an aqueous medium containing binder resin fine particles and colorant fine particles and adjust the temperature to cause salting out and at the same time agglomerate and fuse. Salting out, agglomeration, fusing process to form,
(4) A filtration and washing process for separating magenta toner particles from the aqueous medium and removing a surfactant from the magenta toner particles.
(5) a drying step of drying the washed magenta toner particles;
(6) adding an external additive to the dried magenta toner particles;
Consists of

  Here, the “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

  In the colorant fine particle forming step, a dispersion of colorant fine particles in which the colorant fine particles are dispersed in an aqueous medium by mechanical energy is prepared, and as a disperser for performing oil droplet dispersion by mechanical energy, The present invention is not limited, and examples thereof include a stirring device “CLEARMIX” (manufactured by M Technique Co., Ltd.) equipped with a rotor that rotates at high speed, an ultrasonic disperser, a mechanical homogenizer, a manton gourin, and a pressure homogenizer.

The colorant fine particles in the dispersion prepared in the colorant fine particle forming step preferably have a volume-based median diameter in the range of 10 to 500 nm, more preferably 100 to 300 nm, and particularly preferably 100 to 200 nm. It is.
The method for controlling the volume-based median diameter of the colorant fine particles to 10 to 500 nm can be controlled, for example, by adjusting the magnitude of the mechanical energy described above.

  The binder resin fine particles in the dispersion prepared in the binder resin fine particle polymerization step preferably have a volume-based median diameter in the range of 50 to 200 nm.

[Chain transfer agent]
When the magenta toner particles constituting the magenta toner of the present invention are produced by the emulsion polymerization aggregation method, a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the binder resin. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan, and styrene dimers.

(Polymerization initiator)
When the magenta toner particles constituting the magenta toner of the present invention are produced by the emulsion polymerization aggregation method, the polymerization initiator for obtaining the binder resin is appropriately selected as long as it is a water-soluble polymerization initiator. be able to. Specific examples of the polymerization initiator include persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2 -Amidinopropane) salts), peroxide compounds and the like.

[Surfactant]
Examples of the surfactant used when the magenta toner particles constituting the magenta toner of the present invention are produced by the emulsion polymerization aggregation method include various conventionally known anionic surfactants, cationic surfactants, and nonionic surfactants. Etc. can be used.

  Examples of the anionic surfactant include higher fatty acid salts such as sodium oleate; alkylaryl sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfate salts such as sodium lauryl sulfate; polyethoxyethylene lauryl ether sodium sulfate Polyoxyethylene alkyl ether sulfate salts of polyoxyethylene alkylaryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate, etc. Examples thereof include alkyl sulfosuccinic acid ester salts and derivatives thereof.

  Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.

  Furthermore, examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether, and sorbitan mono Sorbitan higher fatty acid esters such as laurate, sorbitan monostearate, sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate, polyoxyethylene monostearate Polyoxyethylene higher fatty acid esters such as glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride Ethers; polyoxyethylene - polyoxypropylene - and the like block copolymer.

[Flocculant]
Examples of the aggregating agent used when the magenta toner particles constituting the magenta toner of the present invention are produced by an emulsion polymerization aggregation method include alkali metal salts and alkaline earth metal salts. Examples of the alkali metal constituting the flocculant include lithium, potassium, and sodium, and examples of the alkaline earth metal constituting the flocculant include magnesium, calcium, strontium, and barium. Of these, potassium, sodium, magnesium, calcium, and barium are preferable. Examples of the counter ion (anion constituting the salt) of the alkali metal or alkaline earth metal include chloride ion, bromide ion, iodide ion, carbonate ion and sulfate ion.

〔Release agent〕
The magenta toner particles constituting the magenta toner of the present invention may contain a release agent that contributes to suppression of the offset phenomenon. Here, the release agent is not particularly limited. For example, polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, carnauba wax, sazol wax, rice wax, candelilla wax, Examples include jojoba oil wax and beeswax wax.

  As a method for incorporating a release agent into magenta toner particles, a dispersion liquid (wax emulsion) of release agent fine particles is added in the salting out, agglomeration, and fusing steps to form magenta toner particles, and binder resin fine particles are added. In the method of salting out, agglomerating, and fusing the colorant fine particles and the release agent fine particles, and the salting out, aggregating, and fusing steps for forming the magenta toner particles, the binder resin fine particles containing the release agent are colored. Examples of the method include salting out, agglomerating and fusing agent fine particles, and these methods may be combined.

  The content ratio of the release agent in the magenta toner particles is usually 0.5 to 5 parts by mass, preferably 1 to 3 parts by mass with respect to 100 parts by mass of the binder resin. When the content of the release agent is less than 0.5 parts by mass with respect to 100 parts by mass of the binder resin, a sufficient offset prevention effect cannot be obtained, while on the other hand, 5 parts by mass with respect to 100 parts by mass of the binder resin If it is larger, the resulting magenta toner has low translucency and color reproducibility.

[Charge control agent]
The magenta toner particles constituting the magenta toner of the present invention may contain a charge control agent. Here, the charge control agent is not particularly limited, and various substances that give a positive or negative charge by triboelectric charging can be mentioned. For example, as a negatively chargeable charge control agent used for magenta toner particles, Colorless, white or light charge control agents can be used so as not to adversely affect the color tone and translucency of the magenta toner. Preferred examples of such charge control agents include metal complexes of salicylic acid derivatives such as zinc and chromium (salicylic acid metal complexes), calixarene compounds, organoboron compounds, and fluorine-containing quaternary ammonium salt compounds. . Specifically, examples of the salicylic acid metal complex include those disclosed in, for example, JP-A Nos. 53-127726 and 62-145255, and examples of calixarene compounds include, for example, JP-A No. 2-201378. What is disclosed in Japanese Patent Laid-Open No. 2002-221967, for example, as disclosed in JP-A-2-221967, and as a fluorine-containing quaternary ammonium salt compound, for example, disclosed in JP-A-3-1162. Can be mentioned.
The content ratio of the charge control agent in the magenta toner particles is usually 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin.
Examples of the method of incorporating an internal additive such as a charge control agent into the magenta toner particles include the same method as the method of incorporating the above-described offset preventive agent.

<Magenta toner particle size>
The particle size of the magenta toner of the present invention is preferably 4 to 10 μm, and more preferably 6 to 9 μm, for example, on a volume basis median diameter. This average particle size can be controlled by the concentration of the coagulant (salting out agent) used, the amount of organic solvent added, the fusing time, and the composition of the polymer.
When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of magenta toner is measured and calculated using a measuring device in which a data processing computer system (Beckman Coulter) is connected to "Coulter Multisizer TA-III" (Beckman Coulter). Is. Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing magenta toner). Then, ultrasonic dispersion was performed for 1 minute to prepare a magenta toner dispersion, and this magenta toner dispersion was placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Inject with a pipette until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter.

<External additive>
The above magenta toner particles can constitute the magenta toner of the present invention as they are. However, in order to improve fluidity, chargeability, cleaning properties, etc., the magenta toner particles are provided with a fluid which is a so-called post-treatment agent. The magenta toner of the present invention may be constituted by adding an external additive such as an agent and a cleaning aid.

As the post-treatment agent, for example, inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium Inorganic titanic acid compound fine particles such as zinc acid are listed. These can be used individually by 1 type or in combination of 2 or more types.
These inorganic fine particles are preferably subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.

  The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the magenta toner. In addition, various external additives may be used in combination.

(Developer)
The magenta toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the magenta toner of the present invention is used as a two-component developer, the carrier is a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of the metal and a metal such as aluminum or lead. Magnetic particles can be used, and ferrite particles are particularly preferable. Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.
The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins. Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 20 to 60 μm. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  Preferred carriers include a coated carrier using a silicone resin, a copolymer resin (graft resin) of an organopolysiloxane and a vinyl monomer or a polyester resin as a coating resin from the viewpoint of spent resistance. Coat carrier coated with resin obtained by reacting isocyanate with copolymer resin (graft resin) of organopolysiloxane and vinyl monomer from the viewpoint of durability, environmental stability and spent resistance Are preferable.

  According to such a magenta toner, the magenta colorant basically comprises a specific rhodamine compound or a lake salt thereof, so that it has an appropriate hue angle and has a high saturation and a vivid color tone with no color turbidity. Primary color or secondary color image can be formed, and a color close to that of a photographic image can be reproduced, and the specific rhodamine compound or its lake salt has a specific hydrophobic structure. By having it, the humidity dependency of charging can be lowered, and fluctuations in the charge amount can be suppressed even in a high-temperature and high-humidity environment. Furthermore, sufficient fastness to light and heat can be obtained, and excellent storability can be obtained.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.
In the following examples, the volume-based median diameter is “MICROTRAC UPA-150” (manufactured by HONEYWELL), the sample refractive index is 1.59, the sample specific gravity is 1.05 in terms of spherical particles, and the solvent refractive index is The measurement was performed under the measurement conditions of 1.33, solvent viscosity of 0.797 at 30 ° C, and 1.002 at 20 ° C. The zero point adjustment was performed by introducing ion exchange water into the measurement cell.

<Toner Preparation Example 1 (Crushing Method)>
100 parts by mass of a polyester resin (weight average molecular weight (Mw) 20,000), which is a condensate of bisphenol A-ethylene oxide adduct, terephthalic acid, and trimellitic acid, magenta coloring represented by the above formula (1-a) 2 parts by mass of the agent [1-a], 6 parts by mass of pentaerythritol tetrastearate as the release agent, and 1 part by mass of boron dibenzylate as the charge control agent were put into a “Henschel mixer” (Mitsui Miike Mining Co., Ltd.) Then, the peripheral speed of the stirring blade was set to 25 m / second, and the mixture was mixed for 5 minutes.
Next, the mixture is kneaded with a twin-screw extrusion kneader, then coarsely pulverized with a hammer mill, then pulverized with a turbo mill pulverizer (manufactured by Turbo Kogyo Co., Ltd.), and further finely classified with an airflow classifier utilizing the Coanda effect. By performing the treatment, colored particles [1] having a volume-based median diameter of 5.5 μm were obtained.
Next, 0.6 parts by mass of hexamethylsilazane-treated silica (average primary particle size: 12 nm) and 0.8 parts by mass of n-octylsilane-treated titanium dioxide (average primary particle size: 24 nm) were added to the colored particles [1]. Then, using a “Henschel mixer” (manufactured by Mitsui Miike Mining Co., Ltd.), an external additive is added under the conditions of a peripheral speed of a stirring blade of 35 m / second, a processing temperature of 35 ° C., and a processing time of 15 minutes. Was made.

<Toner Preparation Example 2 (Emulsion Association Method)>
(1) Preparation of colorant fine particle dispersion 11.5 parts by mass of sodium n-dodecyl sulfate was added to 160 parts by mass of ion-exchanged water, and dissolved and stirred to prepare an aqueous surfactant solution. In this surfactant aqueous solution, 2 parts by mass of magenta colorant [1-a] is gradually added, and dispersion treatment is performed using “Clearmix W Motion CLM-0.8” (manufactured by M Technique Co., Ltd.). A dispersion of colorant fine particles [2] having a volume-based median diameter of 280 nm (colorant fine particle dispersion [2]) was prepared.

(2) Preparation of resin fine particles for core part a. First stage polymerization 4 parts by mass of an anionic surfactant [W] represented by the following formula (W) together with 3040 parts by mass of ion-exchanged water are charged into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device. A surfactant aqueous solution was prepared.
Formula (W): C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na
In this surfactant aqueous solution, a polymerization initiator solution in which 10 parts by mass of potassium persulfate (KPS) was dissolved in 400 parts by mass of ion exchange water was added, the temperature was raised to 75 ° C., and then 532 masses of styrene. The monomer mixture [a] consisting of 1 part, n-butyl acrylate 200 parts by weight, methacrylic acid 68 parts by weight and n-octyl mercaptan 16.4 parts by weight was dropped into the reaction vessel over 1 hour.
After the monomer mixture [a] is dropped, the system is heated and stirred at 75 ° C. for 2 hours to perform polymerization (first stage polymerization), and resin fine particles having a weight average molecular weight of 16,400 [A1] was produced.
b. Second stage polymerization In a flask equipped with a stirrer, a single unit consisting of 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan. The monomer mixture solution [b] was added, and then 93.8 parts by weight of paraffin wax “HNP-57” (manufactured by Nippon Wax Co., Ltd.) was added as a release agent, and heated to 90 ° C. to dissolve, A monomer solution [c] was prepared.
On the other hand, an aqueous surfactant solution in which 3 parts by mass of an anionic surfactant [W] was dissolved in 1560 parts by mass of ion-exchanged water was prepared and heated to 98 ° C. A mechanical type having a circulation path after adding 32.8 parts by mass (in terms of solid content) of the resin fine particles [A1] to the surfactant aqueous solution and further adding the monomer solution [c]. Emulsified particle dispersion [d] containing emulsified particles having a dispersed particle diameter of 340 nm was prepared by mixing and dispersing for 8 hours with a disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.).
Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate is dissolved in 200 parts by mass of ion-exchanged water is added to this emulsified particle dispersion [d], and this system is heated and stirred at 98 ° C. for 12 hours. Thus, polymerization (second stage polymerization) was performed to produce resin fine particles [A2] having a weight average molecular weight of 23,000.
c. Third-stage polymerization A polymerization initiator solution prepared by dissolving 5.45 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water is added to the resin fine particles [A2] obtained by the second-stage polymerization described above, and 80 ° C. The monomer mixture [e] consisting of 293.8 parts by mass of styrene, 154.1 parts by mass of n-butyl acrylate, and 7.08 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. .
After completion of the dropwise addition, the mixture is heated and stirred for 2 hours to perform polymerization (third stage polymerization). After the polymerization is completed, the core part resin fine particles [1] having a weight average molecular weight of 26,800 are cooled to 28 ° C. Produced.

(3) Production of Resin Fine Particles for Shell In Production Example 1 of the fine resin particles for the core part, the monomer mixed solution [a] is 624 parts by mass of styrene, 120 parts by mass of 2-ethylhexyl acrylate, 56 parts by mass of methacrylic acid. Resin fine particles [1] for shells were prepared in the same manner except that the monomer mixture was changed to a monomer mixture [f] composed of 16.4 parts by mass of n-octyl mercaptan.

(4) Preparation of Ultraviolet Absorber Dispersion Solution 11.5 parts by mass of sodium n-dodecyl sulfate was added to 160 parts by mass of ion-exchanged water, and dissolved and stirred to prepare an aqueous surfactant solution. In this surfactant aqueous solution, 2 parts by mass of an ultraviolet absorber represented by the following formula (X) is gradually added, and dispersed using “Clearmix W Motion CLM-0.8” (M Technique Co., Ltd.). The ultraviolet absorber dispersion liquid [1] was prepared by performing the treatment.

(4) Preparation of toner a. Formation of core particles In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 420.7 parts by mass of resin fine particles for core part [1] (solid content conversion), 900 parts by mass of ion-exchanged water, coloring 200 parts by mass of the agent fine particle dispersion [1] and 120 parts by mass of the ultraviolet absorbent dispersion [1] were added and stirred. After adjusting the temperature in the reaction vessel to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 8-11. Next, an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate was dissolved in 1000 parts by mass of ion-exchanged water was added at 30 ° C. over 10 minutes with stirring. After standing for 3 minutes, the temperature was raised and the system was heated to 65 ° C. over 60 minutes. In this state, the average particle diameter of the associated particles was measured using “Multisizer 3” (manufactured by Coulter), and when the volume-based median diameter became 5.5 μm, 40.2 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 1000 parts by mass of exchange water is added to stop the particle growth, and further, as a ripening treatment, the liquid temperature is set to 70 ° C. and the mixture is heated and stirred for 1 hour to continue the fusion, thereby causing core particles [ 1] was produced. The average circularity of the core particle [1] was measured by “FPIA2000 (manufactured by Systex)” and found to be 0.972.
b. Next, the above reaction system is set to 65 ° C., and 96 parts by mass of resin fine particles for shell [1] are added, and 2 parts by mass of magnesium chloride hexahydrate is dissolved in 1000 parts by mass of ion-exchanged water. After the aqueous solution was added over 10 minutes, the temperature was raised to 70 ° C. and stirred for 1 hour to fuse the resin fine particles for shell [1] to the surface of the core particles [1], and then at 75 ° C. An aging treatment was performed for 20 minutes to form a shell layer.
Thereafter, an aqueous solution in which 40.2 parts by mass of sodium chloride was dissolved in 1000 parts by mass of ion-exchanged water was added to stop the formation of the shell layer. Further, the colored particles produced by cooling to 30 ° C. at a rate of 8 ° C./min are filtered, washed repeatedly with ion exchange water at 45 ° C., and then dried with hot air at 40 ° C. Colored particles [2] having
c. External additive addition treatment Next, hydrophobic silica (number average primary particle size = 12 nm, hydrophobization degree = 68) is added to the colored particles [2] at a ratio of 1% by mass, and hydrophobic titanium oxide ( Number average primary particle size = 20 nm, hydrophobization degree = 63) is added at a ratio of 1% by mass, mixed by “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.), and then sieved with 45 μm openings. Thus, coarse particles were removed to prepare a toner [2].

<Toner Preparation Examples 3 to 9 (Emulsion Association Method)>
In Toner Preparation Example 2, magenta colorant [1-a] is represented by magenta colorant [1-b] represented by formula (1-b) and formula (1-c), respectively. Magenta colorant [1-c], magenta colorant [1-d] represented by the above formula (1-d), magenta colorant [e] represented by the following formula (e), and formula (f) Other than having changed into the magenta colorant [f] represented by the following formula (g), the magenta colorant [g] represented by the following formula (h) Thus, toners [3] to [9] were produced. The toners [6] to [9] are for comparison.

(Preparation of developer)
To each of the toners [1] to [9], a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin is mixed so that the toner concentration becomes 6% by mass, and a two-component developer [1]. To [9] were prepared. Developers [1] to [5] relate to the present invention, and developers [6] to [9] are for comparison.

<Examples 1-5, Comparative Examples 1-4>
Using these developers [1] to [9], “bizhub C250” (manufactured by Konica Minolta Business Technologies Co., Ltd.) is used to evaluate the following (1) to (5), and the developers [1] to [9] Using the “DIALTA Di350” (manufactured by Konica Minolta Co., Ltd.), the following (6) was evaluated. The results are shown in Table 1.

(1) Saturation An image in which the amount of magenta toner adhering was changed in the range of 0.1 to 1.0 mg / cm ² on the transfer paper was formed using a color difference meter “CM-2002” (manufactured by Minolta). From the L ^* a ^* b ^* color space diagram of this image, the saturation C ^* was calculated by the following formula (I).
Formula (I): Saturation (C ^* ) = [(a ^* ) ² + (b ^* ) ² ] ^1/2
However, in the above formula (I), a ^* and b ^* represent the values of the a ^* coordinate and b ^* coordinate, respectively.
In the present invention, evaluations were made such that the value of chroma C ^* was 70 or more was evaluated as “◎”, the value of 60 or more and less than 70 was evaluated as “◯”, and the value of less than 60 was evaluated as “Δ”.

(2) Humidity dependence of charging After each sample is left in a low temperature and low humidity environment (temperature 10 ° C, humidity 15% RH) and a high temperature and high humidity environment (temperature 30 ° C, humidity 85% RH) for at least 24 hours, The amounts QL and QH were measured by a method called “suction type Faraday cage method”, and QL-QH was calculated as a charge amount fluctuation range related to humidity dependency.
The “suction type Faraday gauge method” is a method in which magenta toner on the developing roll is sucked and collected directly into a Faraday cage using a powerful air suction device, and the charge amount is measured.
The case where the fluctuation amount of the charge amount related to the humidity dependency is less than 10 μC / g is indicated by “◎”, the case where it is 10 μC / g or more and less than 20 μC / g is indicated by “◯”, and the case where it is 20 μC / g or more is indicated by “X”. evaluated.

(3) Charging stability in long-term use Print 100,000 sheets in a high-temperature and high-humidity environment (temperature 30 ° C, humidity 85% RH), and measure the charge amount at the initial stage and after printing 100,000 sheets by the suction-type Faraday cage method. did.
“◎” if the decrease in charge amount after printing 100,000 sheets with respect to the initial charge amount is less than 5 C / g, “◯” if it is 5 C / g or more and less than 10 C / g, 10 C / g or more The case where it was was evaluated as "x".

(4) Heat-resistant storage property Take 20 g of toner in a sample tube, shake it 500 times with a tapping denser, leave it in an environment of 55 ° C. and 30% RH for 24 hours, and then put it in a 48-mesh sieve and keep it constant. Sifting was performed under vibration conditions, and the ratio of the amount of toner remaining on the mesh was measured in units of mass%, and this was defined as the toner aggregation rate.
When the toner aggregation rate is less than 15% by mass, “◎”, when it is 15% by mass or more and less than 40% by mass, “◯”, when it is 40% by mass or less and less than 60% by mass, “Δ”, at 60% by mass or more. If there was, it evaluated as "x".

(5) Hygroscopic resistance After the sample (toner) was previously dried in a vacuum dryer for 24 hours and then conditioned for 24 hours in a high temperature and high humidity environment (temperature 30 ° C., humidity 80% RH), the moisture content was as follows: Was measured.
When the water content was less than 1.5% by mass, “◯” was evaluated. When 1.5% or more and less than 2.0% by mass, “Δ” was evaluated, and when 2.0% by mass or more, “X” was evaluated. .
When the water content was less than 2.0% by mass, no image defect was caused by water vapor generated from the toner during heat fixing.
-Measurement of moisture content-
The moisture content of the sample is measured by an automatic thermal vaporization moisture measuring system “AQS-724” comprising a Karl Fischer moisture meter “AO-6, AQI-601” (interface for AQ-6) and a heating vaporizer “LE-24S”. ”(Manufactured by Hiranuma Sangyo Co., Ltd.), 0.5 g of the sample that was allowed to stand for 24 hours in an environment of 20 ° C./50% RH was accurately weighed into a 20 ml glass sample tube, and the Teflon (registered trademark) The silicone rubber packing was used to seal, and the amount of water present in the sealed environment was measured under the following measurement conditions and reagents. Furthermore, two empty samples were measured simultaneously in order to correct the moisture content in the sealed environment.
Sample heating temperature: 110 ° C
-Sample heating time: 1 minute-Nitrogen gas flow rate: 150 ml / min-Reagent: Counter electrode solution (catholyte); Hydranal Coulomat CG-K (HYDRANAL (R) -Coulomat CG-K), generation solution (anolyte): Hydranal Coulomat AK (HYDRANAL (R) -Coulomat AK)

(6) Offset resistance A digital copying machine “DIALTA Di350” (manufactured by Konica Minolta) equipped with an oilless fixing device is loaded with a developer, the fixing speed is set to 300 mm / sec, and the fixing temperature is 90 to 150 ° C. In this range, the halftone image was printed on high-quality paper while changing in increments of 5 ° C., and the occurrence state of the offset was visually observed, and the fixing temperature when the high temperature offset occurred was defined as the offset temperature.
When the offset temperature was 140 ° C. or higher, the evaluation was “◎”, when the offset temperature was 130 ° C. or higher and lower than 140 ° C., “◯”, and when the offset temperature was 120 ° C. or higher and lower than 130 ° C., the evaluation was “X”.

  As described above, according to the developers [1] to [5] according to Examples 1 to 5, excellent saturation, high moisture absorption resistance and good chargeability can be obtained, and high heat storage stability can be obtained. It was confirmed that high offset resistance was obtained.

Claims (2)

A magenta toner for developing an electrostatic image comprising at least a binder resin and a magenta colorant,
A magenta toner for developing an electrostatic image, wherein the magenta colorant comprises a rhodamine compound represented by the following general formula (1) or a lake salt thereof.

[In the general formula (1), R ^{1 to} R ⁴ are each an optionally substituted alkyl group or alkenyl group having 1 to 6 carbon atoms, and R ⁵ is a carbon number having 5 to 20 carbon atoms. An alkyl group, an alkenyl group or —OR ⁶ (wherein R ⁶ is an alkyl group, alkenyl group or aryl group having 5 to 20 carbon atoms). ] The rhodamine compound contained in the magenta colorant is such that R ⁵ in the general formula (1) is —OR ⁶ , R ⁶ is a cyclohexyl group, and R ^{1 to} R ⁴ are each an alkyl having 3 to 6 carbon atoms. The magenta toner for developing an electrostatic charge image according to claim 1, which is a group or an alkenyl group.